As a rule, I'll try any beer once, but I just cannot abide the cheap macro stuff. Luckily, there's a local brewpub that has $2 pints on Mondays, so I don't have to.
My personal favorites are all dark - Guinness was my first love (the imported extra stout was the first beer I ever had), so stouts generally rock my face off (Samuel Smith / Rogue / Young's / Schlafly). New Belgium 1554 was my favorite in college, but I haven't had it in a long while. They also make La Folie, one of the craziest beers I've ever tasted (Belgian Sour Brown, they called it ?). A well made porter hits the spot from time to time as well; Great Divide St. Bridget's is my benchmark for it. Others I'm fond of include Newcastle Brown, Rogue Hazelnut Brown, Heineken Dark, Warsteiner Dunkel, McEwan's Scotch Ale, Sam Adams Black Lager, and Shiner Bock.
Maybe off topic, but in lieu of getting a tree for Christmas, I usually just deck out a keg instead (or two, or
three...).